Daughter-Producing Men

Everyone has parents, you still need a man and a woman to make a baby. Not only that, but if you have siblings, there’s a pretty good chance at least one is the opposite sex. Look at your parent’s siblings and you’ll see the same. Your mom has brothers, your dad sisters. Then there are families that don’t fit. It’s a single sex family. The mother has all sisters, so does the father. They only have daughters themselves. The daughters’ kids? All girls again. Maybe the husbands only have sisters. It’s like the men exist only to produce women. I know one family like this, except for the required father there are three generations of women. Another two families had five or six daughters before having a son. The next kid? You guessed it, a daughter. I wouldn’t be surprised if male-dominated families exist too.

What’s the deal with these single sex families?

In February the New York Times published an article describing changes in behavior when women ovulate. Lap-dancers recieve higher tips, men rate women as more attractive, the pitch of a woman’s voice rises. These changes don’t happen if a woman is on birth control. What if there’s something similar at work for sex-selection in children? Here are some off the cuff possibilities:

Daughter-Producing Men:

1) Men produce more female-sperm (sperm that would result in female offspring) than male. As a result they’re more likely to have daughters

2) Men produce the same amount of female and male sperm, but the male sperm dies faster, leaving more female sperm available

2) The eggs don’t discriminate but the body does, rejecting the fetus/zygote early on. These women would be prone to super-early miscarriages, even before she learned about the pregnancy.

3) Some women are just attracted to daughter-producing men. It’s in the phermones. Whether a woman’s eggs discriminate or not, somehow a woman can sense the daughter producing potential of a man, and seeks him out. [Likewise, the man wants daughters and can sense out the daughter-friendly women whose eggs or bodies are predisposed to having daughters].

Just reverse everything if you want a son-producing man.

Of course, this can (and likely is) way off base and totally wrong. I’m sure someone in the scientific world has written on it.

3 Responses

I’m sorry. I’m no scientist but isn’t this just about randomness? During intercourse men release millions of sperm cells, some of which carry xx chromosomes and some of which carry xy. The chances may seem more remote to have all boys or all girls (like flipping a coin and coming heads three or four times in a row) but I don’t think that it requires elaborate theories; given the number of times the “coin toss” is taking place across humanity, it seems unsurprising that all manner of outcomes occur. Furthermore, given that most families don’t have that many kids, it’s also not so improbable to have one family where all the kids are of the same gender. Coming up heads three times in a row (and the average American family has less than three kids) is much more probable than nine or ten times in a row. I’m curious to hear a rationale as to why you thought this required any explanation other than chance?

The sex ratio at birth to favor males, slightly more males are born than females. Females live longer, and males were more likely to die in war or hunting, which eventually evens out the ratio. It seems we’ve evolved some system for producing more male children. I’m curious what that is and how it operates. The decrease in sex ratio in the United States and Japan over the last 40 years (assuming that’s a large enough dataset) also points to something beyond mere randomness.

Like you I’m no scientist and my stats background is very scant, but can something be random across a large subset but not random on individual items within the set? Maybe over the course of humanity sex is essentially random. That’s because there are some individuals who are 50/50 but still others who are predisposed to children of the same sex. What’s the mechanism for choosing within those individuals? A similar example might be diversity in education. We know there are right wing and left wing colleges, colleges which are predominantly religious or non-religious, black or white. Those individual schools are not diverse, but they allow for diverse education overall.

Last, I wonder if an evolutionary argument can be made in favor of female children. Male children (fight, support the family, etc) have many arguments, but I suspect some arguments exist for women too. In which case, some evolutionary mechanism is at work, and like the above, what’s the mechanism?

I should note that I was struck by the observation and then tried formulating theories. But having been struck by the observation and finding it interesting, I was inclined not to think it pure randomness.